Flow Cytometry is an important analytical and cell purification tool in cancer and immunological research. Modern cancer analysis requires innovative procedures that include both imaging methods and non-imaging analysis, such as that provided by flow cytometry. Flow cytometry allows the isolation of pure cell populations comprising less than 0.01 % of a complex mixture. In addition, as an analytical tools it permits statistical analysis of cell populations and allows for more precise measurement of changes in protein presence and expression, DMA and cell cycle changes, cell function changes, apoptosis, intracellular protein expression, and gene transfection for example. Innovative methods that contribute to modern cancer research include gene expression detection with green fluorescent protein, isolation of transfected cells, isolation of stem cells, FRET (Fluorescence Resonance Energy Transfer), multi parameter cytometry, apoptotic effect of chemotherapy, multi-drug resistance evaluation, and minimal residual disease detection. The recently upgraded high-speed cell sorter, located in Cancer Institute space at the Portland Veterans Affairs NW Cancer Research Center, is capable of measuring 10 parameters at rates of up to 25,000 cells per second. The Flow Cytometry Shared Resource (FCSR) provides technical expertise, trained personnel, and technical services in flow cytometry to meet the needs of OHSU Cancer Institute members.